1. Field of the Invention
This invention in general is related to equipment for separating plant materials according to their relative capacity for floating in water. In particular, it pertains to flotation apparatus for extracting clean chili-pepper pulp from seeds, stems, leaves, branches, and other debris.
2. Description of the Related Art
The principle of flotation has been known and utilized in separation processes for a long time. In essence, the difference in the capacity of different materials to float in a given fluid is exploited in order to separate them. If one material remains afloat while all others sink, that material can easily be extracted from the others by skimming the surface of the fluid. Similarly, if one material sinks while the others float, it can be separated by withdrawing the material from the bottom of the process vessel.
Clearly, the difference in density between materials in a mixture is an important factor in any flotation process, but other factors affect process performance, such as particle porosity (which may produce changes in the effective specific gravity of the material during the flotation process), particle shape, size, and surface tension of the liquid. Accordingly, over decades of experimentation, chemical and mechanical agents have been developed to improve specific flotation processes for various industrial applications. For example, chemicals that enhance the flotation of a particular material in a mixture are used routinely to extract valuable products in the mining industry. Similarly, air sparging has been used to improve the flotation separation of materials in the food industry. U.S. Pat. No. 4,059,604 (1977), U.S. Pat. No. 4,174,314 (1979), U.S. Pat. No. 4,215,040 (1980) and U.S. Pat. No. 5,305,888 (1994) are examples of flotation processes developed for separating vegetable products from other undesirable plant material.
With reference to chili peppers, their commercial value lies in the pulp, which is the raw material for several chili-pepper consumer products, and in the seeds, which are sold to agricultural producers of the fruit. Thus, the commercial processing of chili peppers necessarily involves the separation of pulp and seeds from the rest of the plant and from other materials that may be collected during harvesting of the pepper. Attempts have been made to harvest peppers by machine, which requires collecting stems and branches with the peppers, and then to separate the pulp and seeds from the rest of the plant using flotation and/or pneumatic equipment, but these experiments have not been successful. The separation has been very difficult to accomplish with conventional flotation techniques because of the very similar density of the fruit parts and the rest of the plant. Thus, in practice, as much as possible of the separation of the fruit from the plant is accomplished by humans at harvest time. The pepper is picked by hand ensuring that as little extraneous material as possible is included, it is crushed into pieces, and then the pulp and seeds are isolated from the rest of the fruit material through a dry screening process.
The cost of harvesting chili peppers by hand is becoming increasingly prohibitive in the United States because of its relatively significant incidence on the overall cost of production of chili-pepper products. In today's world economy, where labor costs are often markedly lower in other countries, it is more and more difficult for U.S. producers to compete with chili-pepper products imported from those countries. Accordingly, any cost improvement in the production cycle of chili peppers would provide a strongly needed form of relief for U.S. producers. In particular, there is an urgent need for a solution to the problem associated with the high cost of harvesting chili peppers by hand.